This is interesting oil and thanks for the post, ssls6. KTM is very specific about recommending this Swiss-made Motorex. I wonder why they recommend a 50-weight at all, since all the moving parts turn on ball or roller bearings--all except the piston/rings, that is. Maybe that's it. Maybe KTM uses pistons with teeny skirts and only 1 ring, and they need the thick oil to help seal that one ring.